Towing an Off Road / Overland FMTV

[VertigoPilot]

unpredictability is part of the problem. Cumulative time without vehicle power may be a factor, age of the internal battery may be a factor, who knows but the person who designed it... I once worked on a radar system that used a keep alive battery on the main processor board. To change the battery you wrote the programming parameters specific to your installation(a lot of info) to a non volatile location, then replaced the battery, then you loaded the parameters back into working memory. But the basic program Operating System was in non volatile memory so the processor would reboot after the battery change. Why they didn’t make this an automatic process and skip the battery altogether is not clear...

You can access the programming with cat et software on the j1939 data bus if the processor is operational(OS running). This allows you to change parameters and view sensor data, but I don’t know if you can access or alter the basic OS. If it bricks itself and wipes the OS in the process of this failure, you might not be able to even access it, and it would probably be something cat specific to reload/force feed the basic OS... This is known as a bootstrap process where you send a specific set of commands in the blind to prep the processor and memory followed by the OS program data, all without any acknowledgement untill it gets rebooted and either runs the loaded software or it doesn’t...

It is simply "amazing" that a military truck would have been built with such a crippling vulnerability, but I suppose I shouldn't be surprised!

 

[VertigoPilot]

unpredictability is part of the problem. Cumulative time without vehicle power may be a factor, age of the internal battery may be a factor, who knows but the person who designed it... I once worked on a radar system that used a keep alive battery on the main processor board. To change the battery you wrote the programming parameters specific to your installation(a lot of info) to a non volatile location, then replaced the battery, then you loaded the parameters back into working memory. But the basic program Operating System was in non volatile memory so the processor would reboot after the battery change. Why they didn’t make this an automatic process and skip the battery altogether is not clear...

You can access the programming with cat et software on the j1939 data bus if the processor is operational(OS running). This allows you to change parameters and view sensor data, but I don’t know if you can access or alter the basic OS. If it bricks itself and wipes the OS in the process of this failure, you might not be able to even access it, and it would probably be something cat specific to reload/force feed the basic OS... This is known as a bootstrap process where you send a specific set of commands in the blind to prep the processor and memory followed by the OS program data, all without any acknowledgement untill it gets rebooted and either runs the loaded software or it doesn’t...

Assuming one has a bricked ECU, how would they go about getting a suitable replacement? Can any CAT dealer provide one once they're provided a serial number for the engine?

And if one wanted to equip themselves with CAT ET and a comm connection package to be able to diagnose their vehicle in the field, would this package do the trick when connected to a laptop PC, or would they also need a military version of the software or license?:

CAT Caterpillar ET Diagnostic Adapter III 2024A/2019C CAT ET 3 Truck Diagnostic Tool With WIFI

www.obdii.shop

 

[Ronmar]

Assuming one has a bricked ECU, how would they go about getting a suitable replacement? Can any CAT dealer provide one once they're provided a serial number for the engine?

And if one wanted to equip themselves with CAT ET and a comm connection package to be able to diagnose their vehicle in the field, would this package do the trick when connected to a laptop PC, or would they also need a military version of the software or license?:

CAT Caterpillar ET Diagnostic Adapter III 2024A/2019C CAT ET 3 Truck Diagnostic Tool With WIFI

www.obdii.shop

Yes, cat should be able to configure a new ECU based on the S/N. And thad looks like what you would need to interface a laptop to a cat ECU...

Your truck has a 3116(mechanical inj) engine, or did you get another truck?

 

[VertigoPilot]

Yes, cat should be able to configure a new ECU based on the S/N. And thad looks like what you would need to interface a laptop to a cat ECU...

Your truck has a 3116(mechanical inj) engine, or did you get another truck?

Yes, I'm considering another truck with a 3126 that cranks well on new batteries, has fresh fuel and primes well, shows good voltage at the PDP, but doesn't appear to be getting any fuel delivered to the cylinders for combustion. As I understand the seller's story, the truck came off auction almost three years ago and hasn't successfully started once since. I'm guessing that the ECU battery will have long since died, and so now no available instructions to allow fuel into the engine.

 

[Ronmar]

Yes, I'm considering another truck with a 3126 that cranks well on new batteries, has fresh fuel and primes well, shows good voltage at the PDP, but doesn't appear to be getting any fuel delivered to the cylinders for combustion. As I understand the seller's story, the truck came off auction almost three years ago and hasn't successfully started once since. I'm guessing that the ECU battery will have long since died, and so now no available instructions to allow fuel into the engine.

Cool!

 

[tennmogger]

This is a good thread for all LMTV owners. Glad it popped back to the top.

Vertigo, if you get the new truck, please share your troubleshooying adventure.

 

[VertigoPilot]

This is a good thread for all LMTV owners. Glad it popped back to the top.

Vertigo, if you get the new truck, please share your troubleshooying adventure.

Will do, though it's looking doubtful at this point that I'll be embarking on that adventure with this particular truck. The seller seems to have an unrealistically-high opinion of the value of a non-running basket case M1078A1 that has gone through two owners and multiple "mechanics" since leaving auction without a successful startup. If I do manage to reach fair number with him, I'll start a thread on its diagnostic and repair.

 

[Ronmar]

Will do, though it's looking doubtful at this point that I'll be embarking on that adventure with this particular truck. The seller seems to have an unrealistically-high opinion of the value of a non-running basket case M1078A1 that has gone through two owners and multiple "mechanics" since leaving auction without a successful startup. If I do manage to reach fair number with him, I'll start a thread on its diagnostic and repair.

Trying to get some of his mechanic money back...